This invention relates generally to electronic devices having wireless communications circuitry, and more particularly, to testing wireless communications circuitry in electronic devices.
Electronic devices such as portable computers and cellular telephones are often provided with wireless communications circuitry. The wireless communications circuitry is operable to transmit and receive radio-frequency signals. The wireless communications circuitry includes amplifier circuitry for amplifying the transmitted radio-frequency signals. The wireless communications circuitry wirelessly communicates using a communications protocol. The wireless communications circuitry transmits radio-frequency signals in a communications band associated with the communications protocol.
Electrical components in the wireless communications circuitry typically exhibit non-linearity. The non-linear electrical components produce undesired radio-frequency components at harmonic frequencies of the communications band (e.g., second order harmonics, third order harmonics, etc.). Undesired signal power at harmonic frequencies may interfere with other radio-frequency communications performed by the wireless communications circuitry.
Electronic devices can be subject to requirements such as regulatory requirements that restrict the amount of signal power produced at harmonic frequencies of a communications band. It can be challenging to design and manufacture electronic devices while ensuring that the electronic devices satisfy such requirements. For example, conventional test systems that test electronic devices can produce imprecise measurements. It would therefore be desirable to provide improved test systems for testing wireless communications circuitry.